In communication systems that are being developed today, such as those based on the IEEE (Institute of Electrical and Electronics Engineers) 802.16 air interface or the WiMAX air interface, emergency calls (e.g., “911” calls) and public safety-related calls may experience delays or call latencies that are particularly undesirable given the time critical situations in which many of these calls are made. One reason for this is that these communication networks may not know that a given call is an emergency/public safety-related call until the mobile station (MS) makes two or three transmissions to the network within a contention phase of the MS's ranging process. The ranging codes used by MSs could be partitioned into emergency and non-emergency groups to enable the network to know sooner in the ranging process that a particular call was an emergency call (i.e., only an emergency caller would use a ranging code from the emergency group). However, partitioning codes in such a manner can adversely affect system performance in situations in which signaling of one type floods the system. For example, there may not be enough codes in the emergency group for a large number of emergency responders to simultaneously access the network, while at the same time the group of non-emergency codes may be under-utilized. Thus, new techniques able to better service at least some of the emergency/public safety-related calls would be desirable.
Specific embodiments of the present invention are disclosed below with reference to FIGS. 1-5. Both the description and the illustrations have been drafted with the intent to enhance understanding. For example, the dimensions of some of the figure elements may be exaggerated relative to other elements, and well-known elements that are beneficial or even necessary to a commercially successful implementation may not be depicted so that a less obstructed and a more clear presentation of embodiments may be achieved. In addition, although the signaling flow diagrams and/or the logic flow diagrams above are described and shown with reference to specific signaling exchanged and/or specific functionality performed in a specific order, some of the signaling/functionality may be omitted or some of the signaling/functionality may be combined, sub-divided, or reordered without departing from the scope of the claims. Thus, unless specifically indicated, the order and grouping of the signaling/functionality depicted is not a limitation of other embodiments that may lie within the scope of the claims.
Simplicity and clarity in both illustration and description are sought to effectively enable a person of skill in the art to make, use, and best practice the present invention in view of what is already known in the art. One of skill in the art will appreciate that various modifications and changes may be made to the specific embodiments described below without departing from the spirit and scope of the present invention. Thus, the specification and drawings are to be regarded as illustrative and exemplary rather than restrictive or all-encompassing, and all such modifications to the specific embodiments described below are intended to be included within the scope of the present invention.